Bill de Blasio (right) is sworn in as the mayor of New York City by State Attorney General Eric Schneiderman (left) while his family, Chiara de Blasio (second from left) Dante de Blasio (center) and Chirlane McCray look on at the start of the new year Jan 1. Photo: AP

One era ended and a new one began one minute past midnight Wednesday as Michael Bloomberg turned over the reins of City Hall to New York City’s 109th mayor, Bill de Blasio.

Standing beside his wife, Chirlane McCray, and kids, Chiara and Dante, de Blasio took the oath of office in front of their Park Slope home as a tiny, handpicked crowd looked on.

“I want to say to all of you how grateful we are,” de Blasio said to the crowd, which included Democratic activist Howard Dean and actor Steve Buscemi.

“From the beginning, this has been our family together, reaching out to the people of this city to make a change that we all needed. I want to thank you for having brought us to this moment.”

De Blasio, who had his entire block of 11th Street cordoned off for the occasion, thanked his neighbors. But at least one resident was sick of the charade.

“This is our neighborhood, too, you know,” fumed Richard Elovich, who voted for the mayor.

“He didn’t have to close off all of 11th Street. I’d kind of like to go home sometime tonight.”

New York City Mayor Bill de Blasio and his wife, Chirlane McCray, pictured leaving Bar Toto after he was sworn-in at his home in the Park Slope neighborhood of Brooklyn.Photo: Christopher Sadowski

In an interesting bit of trivia, de Blasio could not become mayor until he paid a $9 registration fee to City Clerk Matt McSweeney.

McSweeney accepted a wad of bills from him, and walked off without counting the money.

De Blasio then headed to a local bar with his family to celebrate.

He becomes the first Democratic mayor of the overwhelmingly Democratic city since David Dinkins in 1993.

De Blasio, who during the campaign blasted many of Bloomberg’s key policies, made a surprise invitation to collaborate with the outgoing mayor during an impromptu encounter on Tuesday.

“When the time comes, we can also talk about some good works we can do together,” said de Blasio, who was checking out preparations for his inauguration at City Hall when Bloomberg happened to walk by.

“I thought we share many, many priorities — and would love to talk about it,” de Blasio added.

Bloomberg was gracious, said he respected de Blasio and told him, in typical Bloomberg fashion, to “do a good job.”

Meanwhile, de Blasio’s ceremonial swearing-in before 5,000 well-wishers at City Hall at noon Wednesday will be the main event.

According to preliminary plans, Harry Belafonte — who will open the ceremony — was to sit right behind the new mayor, while Hillary and Bill Clinton were slated for front-row seats across the aisle.

Actor Steve Buscemi and his wife, Jo Andres, leaving Bar Toto after New York City Mayor Bill de Blasio was sworn-in.Photo: Christopher Sadowski

Also expected in the front row were Bloomberg, Dinkins, Sen. Charles Schumer and two others who will be sworn in — Public Advocate Letitia James and Comptroller Scott Stringer.

Among celebrity supporters of de Blasio, Cynthia Nixon is expected to be in the third row. She was scheduled to introduce “Pippin” star Patina Miller, performing John Lennon’s “Imagine.”

Bill Clinton was to use a Bible once owned by President Franklin D. Roosevelt, on loan from the upstate FDR presidential library, to swear in the mayor.

At City Hall Tuesday, Bloomberg stood on a desk in the bullpen room where he gave a farewell speech and thanked his staff for their work.

“I think it’s . . . fair to say that we’ve shown this country and the world that you can have a great city that includes everyone,” Bloomberg said. “Thank you for everything you’ve done. Thank you on behalf of the 8.4 million people we were lucky to work for.”

Shortly after 5 p.m. Bloomberg left City Hall for the last time as the city’s 108th mayor.